Indiana State University Newsroom

Humans are closely related to chimpanzees and bonobo according to a University of Southern California professor who spoke at Indiana State University to educate students about bonobo primates.

Amy Parish, a biological anthropologist, primatologist, and Darwinian feminist, said that human DNA is about 98 percent identical to bonobos.

"We last shared a common ancestor with them 5 million years ago," Parish said.

People know more about chimpanzees because the scientist Jane Goodall studied them for 45 years in the wild. Bonobos, which look like chimps, aren't as well known, Parish said, but they're in the same genome and a separate species.

Parish studied 120 bonobos in captivity around the world to learn about their social behavior and discovered humans share similar characteristics with bonobos and chimps.

"We could learn something about ourselves by studying our closest living relatives," Parish said. "We are certainly interesting in a lot of ways and some of those ways is that we overlap with our closest living relatives, and in other ways we've diverged from them."

Scientists believe that in order for an adolescent chimpanzee to enter an adult hierarchy, he must dominate every female in the group. Male bonobos differ from male chimps because they don't dominate female bonobos to get into the male hierarchy, according to Parish.

When two male bonobos fight, the mothers rush in to determine the outcome, she said.

"Male bonobos are considered 'mama boys,'" Parish said. "If you have a really high ranking mother, not only do you get into really good areas to eat, but you also get to mate with your mother's friend."

Scientists believe a bonobo mother's rank in the group has an impact on her son's reproductive rank because if she dies the son falls in rank and becomes unimportant.

Female chimps mate 6,000 times during a lifetime to produce six babies. Every male in the group could be the offspring's father since she may mate with everyone in the group.

"It makes it less likely that a male in the group will commit infanticide," Parish said.

Scientists have never seen infanticide in bonobos because females interact differently and they're unusually receptive to baby bonobos that aren't theirs.

"In both bonobos and chimps, it's the females who move away in adolescence to avoid inbreeding and it's the males who get to stay and have the benefit of their kin for life," Parish said.

Parish studied sexual behavior of bonobos and discovered that it's linked to the presence of food and aggression.

"The idea was females need resources to translate into high-quality offspring," Parish said.

In one of her studies, however, she observed that bonobo females didn't have to get food through males but rather took it by force.

Scientists were surprised at Parish's findings because it seemed unusual for females to attack males.

"Everyone thought their male was kind of defective because they were not aware that it was the same pattern for other males," Parish said.

That study caused scientists consider anew the thinking about inter-sexual dynamics because of the female bonobos' relationship to males.

Parish stated that male bonobos are different from male chimps because bonobo males will beg females for their food while male chimps will just take food from the females.

"Male chimps control all the valuable resources," Parish said.

Female bonobos, however, dominate males by forming friendships and alliances, attacking males, having sex with other females, grooming and playing with each other.

"It really pays off for females bonobos to have more power relative to males than their chimpanzee cousins because they don't experience sexual coercion and they don't experience other kinds of male violence," said Parish.